bt: Add option to ena/dis BLE service change registration

Add option to enable/disable automatic registration of BLE Gattc
service change notify. Which sends in parralel
(with user message flow) commands to BLE server which
sometime leads to GATT_BUSY.
(BLE server is able to handle only one command at time)

Closes https://github.com/espressif/esp-idf/issues/1575

Merges https://github.com/espressif/esp-idf/pull/1673

components/bt/Kconfig

@@ -168,6 +168,15 @@ config BLE_SMP_ENABLE
    help
        This option can be close when the app not used the ble security connect.
 
+config BLE_ENABLE_SRVCHG_REG
+    bool "Enable automatic service change notify registration"
+    depends on BLUEDROID_ENABLED
+    default y
+    help
+        This option enables automatic registration of service change notification
+        after connect. Be careful, it can may collide with your command sequences
+        and lead to GATT_BUSY.
+
 config BT_STACK_NO_LOG
     bool "Close the bluedroid bt stack log print"
     depends on BLUEDROID_ENABLED

components/bt/bluedroid/bta/gatt/bta_gattc_act.c

@@ -1635,7 +1635,9 @@ static void bta_gattc_conn_cback(tGATT_IF gattc_if, BD_ADDR bda, UINT16 conn_id,
 
     if ((transport == BT_TRANSPORT_LE) && (connected == TRUE) && (p_conn != NULL) \
          && (p_conn->service_change_ccc_written == FALSE) && (p_conn->ccc_timer_used == FALSE)) {
+#ifdef CONFIG_BLE_ENABLE_SRVCHG_REG
         result = bta_gattc_register_service_change_notify(conn_id, bda, &start_ccc_timer);
+#endif
         if (start_ccc_timer == TRUE) {
             TIMER_LIST_ENT *ccc_timer = &(p_conn->service_change_ccc_timer);
             /* start a 1000ms timer to wait for service discovery finished */